Composite of highly saturated nitrile rubber with fiber, and belt composed thereof

Abstract

A composite comprised of a nitrile group-containing highly saturated copolymer rubber and a fibrous material, which copolymer rubber is a product obtained by hydrogenating the conjugated diene portion of an unsaturated nitrile-conjugated diene copolymer. The highly saturated copolymer rubber has an alkylthio group having 12 to 16 carbon atoms, which include at least three tertiary carbon atoms, and having a sulfur atom which is directly bound to at least one of the tertiary carbon atoms; and the copolymer rubber further has a Mooney viscosity of 15 to 200 and an iodine value not larger than 80. This composite is useful for a belt.

What is claimed is: 
     
       1. A composite comprising a nitrile group-containing highly saturated copolymer rubber and a fibrous material; said nitrile group-containing highly saturated copolymer rubber being a product obtained by hydrogenating the conjugated diene portion of an unsaturated nitrile-conjugated diene copolymer; said highly saturated copolymer rubber having an alkylthio group having 12 to 16 carbon atoms, which include at least three tertiary carbon atoms, and having a sulfur atom which is directly bound to at least one of the tertiary carbon atoms; and said highly saturated copolymer rubber further having a Mooney viscosity of 15 to 200 and an iodine value not larger than 80. 
     
     
       2. A composite as claimed in claim 1, wherein said nitrile group-containing highly saturated copolymer rubber has at least 0.03 mole, per 100 moles of the monomeric units constituting the molecule, of said alkylthio group. 
     
     
       3. A composite as claimed in claim 1, wherein said nitrile group-containing highly saturated copolymer rubber has 0.07 to 0.3 mole, per 100 moles of the monomeric units constituting the molecule, of said alkylthio group. 
     
     
       4. A composite as claimed in claim 1, wherein said alkylthio group is at least one member selected from 1,1-di(2,2-dimethylpropyl)-1-ethylthio group and a 1-(2,2-dimethylpropyl)-1-(2,2,4,4-tetramethylpentyl)-1-ethylthio group. 
     
     
       5. A composite as claimed in claim 1, wherein said alkylthio group is 1,1-di(2,2-dimethylpropyl)-1-ethylthio group. 
     
     
       6. A composite as claimed in claim 1, wherein said unsaturated nitrile-conjugated diene copolymer is comprised of 10 to 60% by weight of acrylonitrile units, 90 to 40% by weight of butadiene units and 0 to 80% by weight of copolymerizable monomer units, and said nitrile group-containing highly saturated copolymer rubber has a Mooney viscosity of 20 to 90. 
     
     
       7. A composite as claimed in claim 1, wherein said unsaturated nitrile-conjugated diene copolymer contains 3 to 20% by weight of a fraction having a number average molecular weight (Mn) of not larger than 35,000. 
     
     
       8. A composite as claimed in claim 1, wherein the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of said unsaturated nitrile-conjugated diene copolymer is in the range of 2.3 to 5.5. 
     
     
       9. A composite as claimed in claim 1, wherein the breadth (.increment.AN) of compositional distribution of unsaturated nitrile in said unsaturated nitrile-conjugated diene copolymer is not larger than 35. 
     
     
       10. A composite as claimed in claim 1, wherein the breadth (.increment.AN) of compositional distribution of unsaturated nitrile in said unsaturated nitrile-conjugated diene copolymer is in the range of 3 to 20. 
     
     
       11. A composite as claimed in claim 1, wherein said unsaturated nitrile-conjugated diene copolymer does not contain a halogen or contains smaller than 3 ppm of halogens. 
     
     
       12. A composite as claimed in claim 1, wherein said unsaturated nitrile-conjugated diene copolymer is comprised, based on the weight of the total monomer units, of 10 to 60% by weight of unsaturated nitrile units, 90 to 40% by weight of conjugated diene units and 1 to 80% by weight of units of an unsaturated carboxylic acid ester or a combination of an unsaturated carboxylic acid ester with a fluorine-containing vinyl monomer. 
     
     
       13. A composite as claimed in claim 1, wherein said nitrile group-containing highly saturated copolymer rubber is vulcanized with a sulfur-containing vulcanizer. 
     
     
       14. A composite as claimed in claim 1, wherein said fibrous material has been treated with an RFL solution comprising an aqueous latex of a nitrile group-containing highly saturated copolymer rubber and a resorcinol-formaldehyde resin. 
     
     
       15. A composite as claimed in claim 1, wherein said nitrile group-containing highly saturated copolymer rubber contained in the RFL solution has substantially the same composition as the nitrile group-containing highly saturated copolymer rubber as adherend combined with the fibrous material for the constitution of the composite. 
     
     
       16. A composite as claimed in claim 1, wherein said unsaturated nitrile-conjugated diene copolymer has 0.1 to 15% by weight, based on the weight of the total monomer units, of units of an ethylenically unsaturated carboxylic acid; and said nitrile group-containing highly saturated copolymer rubber as adherend has 0.5 to 30% by weight, based on the weight of the copolymer rubber, of an oxide of a metal of group II of the periodic table.